Omar Bogle's saved penalty meant that Pompey's automatic promotion hopes are all but over as Barnsley left Fratton Park with a goalless draw.
The Tykes were one of the best teams to come to Portsmouth this season but Kenny Jackett's men matched them and were marginally the better side overall with the 4-3-3 (or 4-1-4-1) formation proving effective.
Jacob Brown missed a couple of good chances for the visitors whilst Bryn Morris headed over a cross from the lively Viv Solomon-Otabor. The latter then squandered the best chance of the half after being played through by Bogle, only to strike his shot straight at goalkeeper Adam Davies.
The second half was an entertaining one but Bogle blew Pompey's big chance to win the game when Solomon-Otabor was felled in the box by Dimitri Cavare.
Whilst his spot kick wasn't as bad as the Bristol Rovers effort on Tuesday, the ball was struck too close and at a good height for Davies who made the save.
Barnsley's best chance of the game came from a corner but Brown's effort struck the woodwork thanks to an excellent save from Craig MacGillivray.
Pompey pressed for a winner after that but couldn't find a way through the Barnsley defence and had to settle for a draw in a game they really needed to win to keep their automatic promotion prospects realistic.
The gap between the two sides remains at five points with with twelve games to play and a good side like Barnsley won't drop too many points between now and the end of the season. Then Sunderland have to be factored in and they're now three points clear of Pompey with a game in hand.
That's not to say that the task is impossible, but the vast majority of Pompey fans will be preparing themselves for the torture of the play-offs come May but at least this performance (and a first clean sheet in 15 league games) will fill them with hope.
Unlike Tuesday night, Pompey played some good football with the front three working well together. Curtis and Solomon-Otabor looked bright whilst Morris and Close kept things ticking in midfield, with Tom Naylor acting as an excellent shield for the back four.
Christian Burgess has silenced his doubters since his costly error against Doncaster and was deservedly named Man of the Match yesterday. Anton Walkes also seems a lot more settled now he has had a run in the team.
As winter comes to an end and spring arrives, there are shoots of recovery for Pompey fans to be optimistic about and hopefully that first win in ten will come against Bradford on Saturday.
But at least this team are showing some fight on the pitch now, and that's something the late, great Micky Kennedy would have been proud of.
Pompey Player Ratings
Craig MacGillivray: 7 - One fantastic save but generally kept goal very well. Safe pair of hands.
Anton Walkes: 7 - Supported the attack well and got some good blocks in too.
Christian Burgess: 8 - Won nearly everything and looks to have shaken off the rust.
Matt Clarke: 6 - Solid but still not at his best.
Lee Brown: 7 - One of his better recent showings.
Tom Naylor: 8 - A "Kennedyesque" performance. Covered the whole pitch.
Viv Solomon-Otabor: 7 - Caused problems but should have done better with the chance he had.
Ben Close: 6 - Looked confident.
Bryn Morris: 7 - Gaining confidence.
Ronan Curtis: 7 - Arguing about the penalty aside, he was worth his place in the team.
Omar Bogle: 5 - Costly penalty and not as threatening as in previous matches.
Substitutes
Alex Bass
Brandan Haunstrup
Dion Donohue
Gareth Evans
Jamal Lowe (Solomon-Otabor 77): N/A - Looked fresh and caused some problems.
James Vaughan (Bogle 84): N/A - Not given enough time.
Oli Hawkins